Electric control



Oct. 10, 1944. wHlTENAcK 2,359,955

ELECTRIC CONTROL Filed May 23, 1942 INVENTOR 'MIRL EWHITENACK P ATT NEYs Patented Oct. 10, 1944 ELECTRIC CONTROL Mirl E. Whitenack, Chicago, Ill., assignor to Hurley Electronic Controls, Inc., a corporation of Illinois Application May 23, 1942, Serial No. 444,245

8 Claims.

This invention relates to an electric control, and. has for an object the provision of an improved method of operating contact-actuated electric control devices to increase their sensitivity and the promptness of their response. The invention has for a further object the provision of an improved form of contact apparatus for carrying out the new method of operation.

Many difierent electric control circuits are actuated by the opening and closing of contacts. If the control circuit operates simply to shift from an off to an on position, or vice versa, a simple make-and-break contact mechanism is generally satisfactory. Some electric controls, however, are responsive or are capable of responding to impulses intermediate an impulse to the full-on position and an impulse to the full-off position. A control circuit of this character is described and claimed in my United States Patent No. 2,208,235, granted July 16, 1940, although no source of intermediate impulses is there disclosed.

The control circuit described in my said patent is actuated by the opening and closing of a contact, particular reference being made to the operation thereby of a pair of mechanically interconnected motors. When the contacts are opened, one of the motors is caused to rotate in one direction, and when the contacts are closed, the other of the motors is caused to rotate in the opposite direction. The control circuit is of such nature as to be capable of responding to an imcold discharge electrodes, and not as contacts. in

pulse intermediate full closure or full opening of the contacts. For example, the control circuit is capable of causing one motor to operate weakly in its direction of rotation, and at the same time to cause the other motor to operate relatively strongly in its opposite direction of rotation. The net result is a rotation of the two motors in the direction caused by the more strongly energized motor, but with a force (or speed) substantially less than if the latter motor were fully energized and the former not energized at all.

I have discovered that a control circuit of the character above described may be caused to impart impulses intermediate a full-on impulse and a full-off impulse, by appropriate construction and operation of the socalled contact apparatus. I have discovered that if the contacts are spaced sufiiciently closely together so that at the potential normally applied thereacross the normal atmosphere therebetween is at all times ionized to a substantial extent, the control circuit may be actuated by movement of the contacts within this close limit of spacing to provide impulses intermediate a full-on impulse and a full-oil impulse the usual sense.

Based on this discovery, the present invention provides a method of operating electric control circuits through the agency of electrode elements, and further provides an improved contact apparatus by means of which the method of the invention may be carried out. The invention provides the improvement, in the operation of an electric control by relative movement of cold contact or electrode elements toward and away frmo each other, which comprises maintaining at all times over the operating range the spacing of the electrode elements sufiiciently close so that at the potential applied thereacross the atmosphere therebetween is ionized to a substantial extent. The electric control is then actuated by movement of the electrode elements toward and away from each other within the close spacing limit necessary to maintain substantial ionization of the atmosphere in the gap between the electrodes. The apparatus by means of which this improvement is achieved comprises at least two electrode elements, and means for moving at least one of said electrode elements toward and away from the other of said elements. The spacing between the electrode elements is maintained sufficiently close over the operating range so that at the potential normally applied thereacross, the normal atmosphere in the gap therebetween is ionized to a substantial extent even at maximum normal separation of the electrode elements. This spacing of the elements advantageously is of the order of 0.0005 inch per volts of potential normally applied thereacross.

The invention will be better understood from the following description considered in conjunction with the accompanying drawing, in which Fig. 1 is a wiring diagram of a control circuit which may be actuated in accordance with the invention;

Fig. 2 is an elevation, partly in section, of a form of contact assembly embodying the features of the invention; and

Fig. 3 is an elevation of another form of contact apparatus embodying the features of the invention.

The electric control circuit shown in Fig. 1 is described and claimed in my aforementioned Patent No. 2,208,235, and forms no part of the present invention. This control circuit, however, is illustrative of the type of potential-controlled control circuits that may be advantageously actuated by the method and apparatus of the invention.

In the circuit shown in Fig. 1, a pair of motors in and H, interconnected by a shaft 12, are supplied with current from a source I3 through reactor units l4 and 55, respectively. Each of the reactors M and I5 is formed with a control winding l6 and {1, respectively. The control windings i6 and H are connected in the anode circuits of grid-control tubes l8 and 99, respectively. The cathode circuits of the tubes I8 and I9 are supplied with power from the source I3 through transformers 20 and 2!. The grids of the two tubes are biased in such a manner that when either one of the tubes is in condition for unrestricted passage of current, the other tube is nonconducting. A "contact unit 22 is connected between the grid of the tube I8 and ground, so

that if the contact unit 22 be fully closed, the grid bias of the tube 18 is such as to permit passage of current through this tube. Conversely if the contact unit 22 be fully open, the grid bias applied to the tube I8 is such as to render this tube non-conducting, whereupon the grid b-ias applied to the tube 19 becomes such as to make the latter tube conducting. The circuit is such that current flows through the motor only when the tube I8 is conducting and so permits current to flow through the associated control winding 16. This occurs when the contact 22 is partially or totally closed. Conversely, when the contact 22 is fully open, the flow of current through motor I0 is cut off by the greatly increased impedance of the reactor l4, and concurrently current flows through motor H and the associated reactor in consequence of the fact that the opening of the contact 22 renders the tube l9 conductive.

The above-described control circuit is of such nature that by reducing somewhat, but not fully to ground potential, the bias potential applied to the grid of the tube l8, the tube I8 becomes partially conducting, and the tube [9 also becomes partially conducting. This permits a current less than full actuating current to flow through both motors In and II, and the shaft I2 is caused to rotate in the direction of rotation of the more strongly energized motor. This result may be achieved by appropriately constructing and op-' erating contact unit 22 in accordance with the present invention. To accomplish this result, the contact points or cold electrodes of the unit 22 are preferably always spaced, but so closely together that at the impressed potential the atmosphere therebetween is ionized to a substantial extent. The maximum separation of the electrodes advantageously is such that when they are separated to the maximum extent the resistance of the ionized gap between them is as high as practical consistent with maintaining ion zation of the atmosphere therein. As the electrodes are moved together, the resistance of the gap decreases until it becomes substantially zero at the point where the electrodes actually touch each other, should they be permitted to touch. However, during operation in accordance with this invention the electrodes are separated at all times. Because of the resistance of the ionized gap between the electrodes, such close spacing of the electrodes permits the grid bias of the tube 18 to be only partially reduced.

The exceedingly minute relative movement of the electrodes may readily be kept within the narrow spacing limits necessary to maintain substantial ionization of the atmosphere between these cold electrodes. The bias potential impressed upon the grid of the tube l8 thus may be increased or decreased with corresponding decrease or increase of the grid bias applied to the tube l9 without actually moving an electrode all the way to either fully closed or fully opened position. Exceedingly minute relative movement of the electrodes thus is adequate to cause one or the other of the motors l0 and II to become the more strongly energized. If the motors l0 and l I are used to open or close a valve to control variation in some desired quantity, for example, or to actuate other apparatus, it is thus apparent that such actuation in an appropriate direction may be eifected in response to exceedingly minute control impulses imparting but trifling movement to an electrode of the unit 22. The sensitivity of the control is thereby rendered exceedingly great, and extremely close regulation of control is efiected. Moreover, the promptness with which the control ircuit responds to a change in the conditions to which the previously employed contact assembly was itself responsive is very much increased, because the t me lag involved in movement of the previously employed contact points from a full-off position to a full-on position is largely eliminated.

Fig. 2 shows a form of contact unit that may be constructed to actuate the control circuit as above described. This contact unit comprises a frame 25 having an expansible bellows 26 secured to the bottom thereof. A nipple 21 is provided for admitting a fluid under positive or negative pressure to the interior of the bellows. A shaft 28 is secured to the top of the bellows 26. A spring 29 connected by appropriate linkage to the shaft 28 and to the top of the frame 25 i provided to bias the bellows 26 mechanically to a chosen. position. Advantageously, the biasing force exerted by this spring is made adjustable by a thumb screw 30. The relation between the downward movement of shaft 28 and the initial application of biasing force thereto can be adjusted by nut 46. The shaft 28' carries a movable cold electrode element 3| and a cooperating stationary cold electrode element 32 is mounted on an electrically non-conducting transverse frame member 33. With the bellows 26 biased substantially to the average pressure of the fluid communicating with the interior of the bellows through the tube 21, small changes in the pressure exerted by the fluid on the bellows causes the bellows to expand or contract and thereby to move the electrode element 3| away from or toward the cooperating electrode element 32.

In accordance with the invention, the spacing of the electrode elements 3! and 32 is made and maintained extremely small-sufficiently small so that at the potential impressed thereacross the 'normal atmosphere therebetween is ionized to a substantial extent. This spacing advantageously is of the order of 0.0005 inch per volts of potential impressed across the gap between the elements. This exceedingly close spacing of the electrode elements should be maintained at all times during operation of the control circuit in order to securethe benefits of the invention. With the adjustments 3!] and 46 above mentioned and sufficiently responsive controls, including the control circuit (Fig. l) the motors i0 and l I, and the Valve 41 or other apparatus actuated thereby to control the pressure of the fluid in line 48 to which the bellows 26 (Fig. 2) is subjected through line 49, this close spacing will normally be maintained over the operating range of movement of the bellows 26 without any special provision there for, i. e., without any maximum or minimum movement limiting stops. This is due to the fact that the prompt response of the control apparatus to even the most minute movement of the movable electrode element insures that. the pressure exerted by the fluid within the bellows will remain sufficiently constant to insure against any substantial movement of the electrode element beyond the limits of the desired range of close spacing. If desired, however, an adjustable maximum stop secured to the shaft 28 may be provided to prevent movement of the contact element 3| farther than desired away from element 32. A corresponding minimum stop could likewise be provided.

Fig. 3 shows a different type of contact apparatus which may embody the features of the invention. This contact apparatus comprises a Bourdon tube 35 mounted on a frame 36 within a case 31. Fluid under positive or negative pressure is admitted to the Bourdon tube through an opening 38 which, for example, could receive a nipple connected to line 49, in the placeof nipple 21 of Fig. 2. A movable contact or cold electrode element 39 is carried at the end of the Bourdon tube. A cooperating stationary contact or cold electric element 40 is mounted on an adjustable carriage 4|. The position of the carriage may be adjusted by manipulation of a knob 42 mounted on a threaded shaft 43 engaging with the carriage. A pointer 44 may be connected to the carriage through suitable gear and linkage mechanism in order to indicate on a scale 45 the pressure prevailing within the Bourdon tube when the elements 39 and 40 are just barely touching.

In this contact apparatus, as in the contact apparatus illustrated in Fig. 2, in the invention contemplates maintaining the spacing between the electrode elements 39 and 40, throughout the normal operating range of the apparatus, always sufiiciently close so that the normal atmosphere between said elements is ionized to a substantial extent. By so doing, the contact mechanism may be employed to secure exceedingly prompt response by a control circuit such as that shown in Fig. 1, and to render the control circuit, motors, and other control apparatus responsive to exceedingly minute variations in the pressure exerted by the fluid on the Bourdon tube instead of a bellow as in Fig. 2.

The forms of contact apparatus responsive to pressure variations of a fluid, as shown in Figs. 2 and 3, are merelyillustrative of the type of contact assemblies that may be constructed and operated in accordance with the invention. Instead of being responsive to ordinary pressure variations, the apparatus shown in the drawing may be filled with a thermally expansible fluid to render the contact assemblies responsive to temperature changes. Many other types of contact apparatus embodying the very closely spaced electrodes of the invention also may be made, as is apparent.

The specific description of the control circuit shown in Fig. 1, and its actuation of motors, likewise is by way of illustration only. Other types of contactor electrode-actuated control circuits may be employed in connection with apparatus constructed and operated according to the invention; and the control circuit may regulate other electrical devices than motors, such, for example, as lights, magnetic apparatus, and the like.

I claim:

1. In an electric control system of the type which is responsive to the magnitude of applied potential, the method of actuating said control system so as to be responsive to extremely small movement of two cold electrode elements relative to each other, which comprises, maintaining said elements separated at all times from each other by a gap of variable length, impressing across said elements and thus across said gap a potential of the order of magnitude of that to which said control system is responsive and subjecting said elements to anormal atmosphere, and limiting the range of movement of said elements With respect to each other so that the gap therebetween is limited to a range of spacing such as to maintain at said impressed potential a substantial degree of ionization of the atmosphere in said gap at all times during operation of said control.

2. In an electric control system of the electronic tube type which is responsive to the magnitude of bias potential applied to a control electrode thereof, the method of actuating said control system so as to be responsive to extremely small movement of a movable cold electrode element with respect to a stationary cold electrode element, which comprises, subjecting said elements to a normal atmosphere, maintaining said elements at all times with a gap of .variable length therebetween, impressing said bias potential on said elements across said gap, and limiting the movement of said movable element with respect to said stationary element 50 that the length of said gap is kept within a range such as to maintain at said impressed potential a substantial degree of ionization of the atmosphere in said gap at all times during operation of said control.

3. The method of actuating a potentialoperated electric control so as to be responsive to extremely small relative moment of a movable cold electrode element with respect to a cooperating stationary cold electrode element, which comprises maintaining said electrode elements separated at all times from each other by a gap of variable length subjecting said elements to a normal atmosphere, impressing a potential across said elements, and limiting the movement of said movable element so that the gap between said elements is limited to a range of spacing such that said potential is suflicient to maintain a substantial degree of ionization of the atmosphere in said gap at all times during operation of said control.

4. In an electric quantity-control system of the type which is responsive to the magnitude of applied potential, the method of actuating said control system so as to be responsive to extremely small movement of a movable cold electrode element with respect to a stationary cold electrode element, which comprises maintaining said electrode elements separated at all times from each other by a gap of variable length, subjecting said elements to a normal atmosphere, automatically moving said movable element in response to variation in the quantity which it is desired to control whereby to form a gap of variable length between said elements, impressing a potential across said elements and thus across said gap, and limiting the maximum movement of said movable element so that the length of said gap is kept within a range such as to maintain at said impressed potential a substantial degree of ionization of the atmosphere in said gap at all times during operation of said control, whereby to efiect extremely close regulation of control of said quantity.

5. The method of actuating a control system according to claim 4, in which the maximum limit of movement of said movable element is of the order of 0.0005 inch per 100 volts of potential impressed across said gap.

6. In ultra-sensitive potential-controlled apparatus the combination which includes, a normally stationary cold electrode element, a movable cold electrode element positioned in close proximity to and in movable cooperative relation with said stationary electrode element, said electrode elements being maintained separated at all times from each other by a gap of variable length, means limiting the normal separation between said elements to the order of 0.0005 inch per 100 volts of potential normally applied between said elements, and means operatively included in said apparatus for moving said movable element toward and away from said stationary element within the limit of said separation, whereby to effect extremely close regulation of control of the operation of said apparatus.

7. In ultra-sensitive potential-controlled apparatus the combination which includes, a normally stationary cold electrode element, a movable cold electrode element at all operating positions closely spaced from said stationary element, normal atmosphere between said elements, said electrode elements being maintained separated at all times from each other by a gap of variable length, means impressing a potential on one of said elements with respect to the other element to ionize said atmosphere between said elements, means limiting the maximum normal separation between said elements to the order of 0.0005 inch per 100 volts of potential thus impressed, and means operatively included in said apparatus for automatically moving said movable element toward and away from said stationary element within said limit of maximum normal separation, whereby to efiect extremely close regulation of control of the operation of said apparatus.

8. In ultra-sensitive potential-controlled apparatus the combination which includes, a normally stationary cold electrode element, a movable cold electrode element closely spaced from and movable toward and away from said stationary element forming a variable gap therebetween, normal atmosphere between said elements, said electrode elements being maintained separated at all times from each other by a gap of variable length, means impressing a potential on one of said elements with respect to the other of said elements sufllcient to ionize said atmosphere between said elements, means limiting the movement of said movable element so that the length of said gap is kept within a range such as to maintain at said impressed potential 2. substantial degree of ionization of the atmosphere in said gap at all times during operation of said apparatus, and means operatively included in said apparatus for moving said movable element toward and away from said stationary element within said range, whereby to effect extremely close regulation of control of the operation of said apparatus.

MIRL E. WHITENACK. 

